Fifty Highlights from Fifty Years

The year 2012 marks the 50th anniversary of the European Southern Observatory (ESO), the foremost intergovernmental astronomy organisation in the world. This very special year provides a great opportunity to look back at ESO’s history through its most important milestones, as it celebrates 50 years of reaching new heights in astronomy. Fifty selected highlights from the first 50 years of ESO’s history are marked below with superscripts. For a comprehensive timeline of ESO’s milestones see this.

The idea of a shared European observatory was discussed for the first time in late spring 19531 by a group of astronomers in Leiden, the Netherlands. They included Walter Baade and Jan Oort, Adrian Blaauw and Otto Heckmann. Oort would later become President of the ESO Committee and Heckmann and Blaauw ESO’s first and second Directors General respectively. From the start, they intended to build an observatory in the southern hemisphere. On 5 October 1962, representatives from five European countries — Belgium, France, Germany, the Netherlands and Sweden — signed the ESO Convention in Paris2. Their signatures represented a formal commitment to establish the European Organisation for Astronomical Research in the Southern Hemisphere, today commonly referred to as the European Southern Observatory.

In late 1963, Heckmann, then acting as ESO’s Director General, concluded an agreement with the Chilean government to establish ESO’s observatory in Chile3. ESO had originally planned to establish itself in South Africa, but site testing indicated that atmospheric conditions were better in the high and dry mountainous regions of the Chilean Atacama Desert. ESO was now set to build the observatory it had planned.

In spring 1964, after site testing, the exact site of the observatory was chosen4, a 2400-metre-high mountain, 600 kilometres north of Santiago de Chile. The site was nicknamed La Silla — the chair — due to its particular shape. The same year, ESO bought the land around the mountain5 from the Chilean government and was given a site in the capital Santiago to build its Chilean headquarters, next to the UN offices in the Vitacura district. In late November 1966, the observatory’s first telescope, 1 metre in diameter, started operations at La Silla6. Others would follow over the next few years, until the official inauguration of the observatory7 by the President of the Republic of Chile, Eduardo Frei Montalva, on 25 March 1969. ESO now officially had its observatory in the southern hemisphere. Yet, even before this, ESO grew, with Denmark joining as the sixth Member State in 19678.

Moving forward to the 1970s, the Organisation passed a number of major milestones. In November 1976, the 3.6-metre telescope, the jewel in the La Silla crown, envisioned since the inception of ESO, started operations9. This had been made possible thanks to a close cooperation with CERN in Switzerland, where ESO’s technical staff had moved in 1970. In 1978, the Quick Blue Survey was completed10 using the 1-metre Schmidt telescope, at La Silla, one of the original telescopes planned for in 1953. This survey was the first of its kind in the southern hemisphere, mapping the sky in detail and providing a basis for future observations. ESO had now completed its original mission to build and equip its observatory in the southern hemisphere with world-class telescopes.

In 1975, the Council, ESO’s sovereign body, decided to build the new headquarters in Garching bei München11, Germany, following an offer by the German government to host ESO. The move was meant to gather all of ESO’s European staff, which was spread out between Geneva and Hamburg, where ESO’s administration had been located since the creation of the Organisation. Construction began even before the German government and ESO formally agreed on the project in 1979, and the new offices, of a very original design, were inaugurated in 198112 in the presence of senior representatives from ESO and its Member States. The move in many ways transformed ESO into a full-fledged intergovernmental organisation, going beyond the role of providing a shared observatory to its Member States.

As the 1980s concluded, ESO had a fully equipped and functional observatory at La Silla, and was already planning its next observatory, set to become a reference in the world of ground-based astronomy. It took ESO ten years to build the highly complex VLT, whose first telescope, named Antu — the Sun in the Mapuche language — saw First Light in May 199820. The official inauguration of the new observatory followed shortly afterwards and on 5 March 1999, the VLT was officially opened21 in the presence of the President of the Republic of Chile, Don Eduardo Frei Ruiz-Tagle. The VLT was now ready to make its contribution.

La Silla meanwhile saw a number of new instruments being added to its telescopes, among which is HARPS, the leading exoplanet hunter, which started operating in 200333.

In 2005, together with the Max Planck Institute for Radio Astronomy and Onsala Space Observatory, ESO built a new telescope, APEX, the Atacama Pathfinder Experiment34, partly based on experience gained from the Swedish-ESO Submillimetre Telescope (SEST) at La Silla in the 80s and 90s. These were ESO’s first steps in millimetre radio astronomy. APEX is designed to study the skies in submillimetre wavelengths. Located on the Chajnantor Plateau at 5000-metre altitude in the Atacama Desert of Chile, APEX was designed as a precursor to a much larger project, ALMA, the Atacama Large Millimeter/submillimeter Array.

In 2001, ESO signed an agreement with North America to build ALMA35 on the Chajnantor Plateau (Japan joined in 2004). This gigantic project came as a merger of three individual observatory projects following site testing from 1995 and onwards. ALMA is the world’s largest observatory project and will be a single telescope composed of 66 high-precision antennas that will study the Universe at millimetre and submillimetre wavelengths. In 2003, the Republic of Chile granted free concession of the land on Chajnantor for the execution of the ALMA project36. In 2006, it was decided that ESO would build ALMA’s headquarters next to ESO’s own Santiago offices in the Vitacura district. ALMA's construction will be completed in 2013, but early scientific observations with a partial array began on 30 September 201137, providing the world with a taster of ALMA’s full capability.

These milestones in ESO’s history have led to a number of major scientific breakthroughs which were made possible thanks to the dedication of ESO’s teams, the quality of its instruments and the ingenuity of the astronomical community. Of these, ten stand out for their significance. They are bound to change over time as ALMA and the ELT become operational, but they are a testimony to the quality of ESO’s various observatories as it celebrates its 50th anniversary.

ESO’s history is filled with many milestones, evidence of the passion and vision of its founding fathers, staff, and the community throughout the years. Over 50 years, ESO has grown beyond its original mission to become the world’s most productive observatory. It carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries and plays a leading role in promoting and organising cooperation in astronomical research. This vision is ESO’s trademark and it is sure to remain the driving force at the heart of ESO’s activities as ESO aims to reach new heights in astronomy in 2012 and beyond.